Fire Conditions Research Articles

Evaluating immaturity risk in young stands of the serotinous knobcone pine (Pinus attenuata)

AbstractAs wildfire becomes increasingly frequent, many serotinous plant populations risk local extirpation if fire recurs prior to sufficient seed accumulation in the canopy (i.e., “immaturity risk”). Following two 2018 wildfires in northwestern California, we studied seed viability, cone production, and postfire regeneration of a serotinous conifer, knobcone pine (Pinus attenuata), with stand ages (time since fire) ranging from 6 to 79 years. Cone density per tree was more strongly associated with tree diameter than age, and cone density was positively related to postfire seedling regeneration. Most of the postfire knobcone pine regeneration established during the first year with high survivorship in the following first postfire year. Adjusting for survivorship, the estimated minimum age for knobcone pine to promote self‐replacement (one recruit per tree) was 9.5 years (or 4.6‐cm dbh) and the probability of reburning at the modern fire rotation of 43 years was 19.8%. Based on our results, we found that immaturity risk was currently low for knobcone pine. Our approach provides a quantitative method to assess immaturity risk in knobcone pine and other serotinous conifer species that can be used to evaluate future risk under rapidly changing climate and fire conditions.

Aerosol radiative forcing of forest fires unprecedented in South Korea (2022) captured by Korean geostationary satellites, GK-2A AMI and GK-2B GEMS

The worst forest fires in Korean history broke out on March 4, 2022 and lasted for ten days. In order to monitor the catastrophic forest fires, Geostationary Korea Multi-Purpose Satellite (GK)-2 A Advanced Meteorological Imager (AMI) and GK-2B Geostationary Environment Monitoring Spectrometer (GEMS) data were used in this study. Aerosol optical depth (AOD) irretrievable for the biomass-burning aerosols produced with water vapor classified as could-contaminated, was reconstructed by ultraviolet aerosol index (UVAI). Afterward, aerosol radiative forcing (ARF) at TOA was finally estimated by the correlation of AOD and surface albedo with ARF. Most of the aerosols drifted toward the East Sea by the prevailing westerly winds, and caused a cooling effect on the atmosphere with a maximum daily average radiative forcing of −69.28 Wm-2. Furthermore, the fire-prone conditions for the unprecedented forest fires were discussed in detail as following aspects; 1) the most severe drought caused by a “triple-dip” La Niña; 2) pressure patterns and topographical features that generate strong winds; 3) coniferous forests prone to fires; and 4) increased human activity following the nationwide COVID-19 vaccination. This study demonstrated that the rapid and effective ARF estimation based on the satellite remote sensing can contribute to a better understanding of ARF in the Earth's radiation budget for the global forest fires that will be more frequent, intense, and longer-lasting due to the human-caused climate and environment changes.

Prescribed burning mitigates the severity of subsequent wildfires in Mediterranean shrublands

BackgroundPrescribed burning (PB) is becoming relevant in fuel reduction and thus fire hazard abatement in fire-prone ecosystems of southern Europe. Yet, empirical evidence on the effectiveness of this practice to mitigate wildfire severity in Mediterranean shrublands is non-existent, despite being the focus of PB efforts in this region. Here, we intended to quantify the protective effect of PB treatment units (2005–2021) to subsequent wildfire severity in shrublands across mainland Portugal, as well as the relative contribution and complex interactions between drivers of wildfire severity in PB-treated areas and untreated neighboring counterparts through Random Forest regression. We leveraged cloud-computing remote sensing data processing in Google Earth Engine to estimate fire severity (PB and wildfire) as the Relativized Burn Ratio (RBR) using Landsat data catalog.ResultsPB treatment was particularly effective at mitigating wildfire severity at the first PB-wildfire encounter in shrublands, with a mean reduction of around 24% in RBR units. Fuel age (i.e., time since prescribed burning) in PB-wildfire intersection areas overwhelmed to a large extent the effect of fire weather, burning probability, and PB severity. The mitigating effect of PB on wildfire severity persisted for a fuel age of around 5 years. However, this effect decreased with increasingly adverse fire weather conditions, such that variation in wildfire severity was somewhat insensitive to fuel age under extreme fire weather. Similarly, the lowest wildfire severity experienced in sites with high burning probability, along with the interaction effect observed between burning probability and fuel age, suggest that repeated PB treatments may be useful in controlling fuel accumulation and mitigating wildfire severity. The relative contribution of fire weather in explaining wildfire severity was exceedingly high in untreated areas, doubling that of the other variables in the model in the absence of PB treatment variables.ConclusionsOur results suggest that the implementation of PB treatments at intervals of less than 5 years is of paramount importance to control fuel build-up and fire hazard under extreme fire weather in productive Mediterranean shrublands. Further research on this topic is warranted in other shrublands worldwide, namely in Mediterranean-type climate regions.

Thermal, Morphological, and mineralogical characterization of ancient potsherds: Insights from activation energy and degradation profiles

The six representative potsherds sourced from the excavated Buddhist site of Udayagiri, Odisha, in eastern India, were studied using analytical characterization techniques of X-ray diffractometry (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), thermogravimetry (TG-DTG), and a porosity study. The analysis has unveiled the clay composition, firing temperatures, and environment along with internal morphology of these potsherds after firing process. The thermal behavior of the pottery samples was meticulously examined and degradation profiles depicted through TG-DTG curve. The activation energy of potsherds was calculated using the Horowitz and Metzger equation, shedding light on the various stages of degradation. Notably, the calculated activation energies for the first stage of degradation ranged from 5.78 to 16.64 kJ/Mole, while for the 2nd/3rd stage degradation, the range was between 2.59 KJ/Mole to 8.38 KJ/Mole, underlining the intricate firing processes involved. This research has successfully estimated firing temperatures across different environmental conditions, spanning from 450 to 900 °C. The pottery fragments were categorized into two distinct varieties following a comprehensive analysis of firing temperature, inclusions, morphological characteristics, firing conditions, and degradation profiles. The multifaceted approach employed in this study has contributed significantly to our understanding of these potsherds' composition and their firing profile.

Synoptic-Scale Wildland Fire Weather Conditions in Mexico

Future climate change is expected to increase the risk and severity of wildland fires in tropical regions. Synoptic-scale fire weather conditions in Mexico were carefully analyzed using 20 years of satellite hotspot and rainfall data, hourly weather data, and various climate data. Fire analysis results showed that eighty-four percent of all fires in Mexico occurred south of 22° N. Southwest Mexico (SWM, N < 22°, 94–106° W) and Southeast Mexico (SEM, N < 22°, 86–94° W), account for 50% and 34% of all fires in Mexico. Synoptic-scale analysis results using hourly data showed that westerly wind sea breezes from the Pacific Ocean blow toward the coastal land areas of the SWM while easterly wind sea breezes from the Caribbean blow into the SEM. The most sensitive weather parameters were “relative humidity” for the SWM and “temperature” for the SEM. The fire-related indices selected were “precipitable water vapor anomaly” for the SWM and “temperature anomaly” for the SEM. The SWM fire index suggests that future fires will depend on dryness, while the SEM fire index suggests that future fires will depend on temperature trends. I do hope that this paper will improve local fire forecasts and help analyze future fire trends under global warming in Mexico.

Fire Tests of Load-Bearing, Light-Steel-Framed Wall Systems Insulated with Polyurethane Foam

This paper presents the details of three fire tests conducted on light-steel-framed (LSF), load-bearing wall systems, which consist of polyurethane insulation injected into the cavities of the steel frame between two or three layers of gypsum fibreboard. To investigate the thermal and structural performance limits under standard fire conditions, observations were made during the tests, and temperatures and vertical displacements were recorded. Although combustible insulation was used, the results obtained are promising for the application of studied LSF wall systems in buildings, where fire resistance of more than 60 min is required.

Structural fire investigation and analysis on rectangular shield tunnel assembled by composite segments

Rectangular shield tunnels have been extensively used in roads, railways, stations, etc. In this paper, the structural responses of rectangular shield tunnel assembled by composite segments under fire were investigated. The elaborate numerical model was established based on the real rectangular shield tunnel and relevant assumptions were proposed based on matters of fact to enhance the computational efficiency of the model. In both ambient and elevated temperature conditions, the reliability of the finite element model is validated by previous experimental results. Afterward, parametric studies were also performed by a series of numerical simulations by varying parameters such as fire curves, loading conditions, and material types. This involved calculating the temperature distribution and internal forces in steel plates and concrete, as well as examining lining deformation, joint opening, and vulnerability. According to the results, during the cooling stage of RABT curve, the joint opening can be reduced by more than 30% on average and up to 50%. Load conditions have a significant effect on the mechanical response of the tunnel structure, especially the deformation. In addition, under the effect of RWS fire curve, the structure of lower-degree concrete is unstable. The results contribute to the fire-resistant design of rectangular shield tunnels assembled with composite segments.

Pervaporation dehydration of an isopropanol aqueous solution using microporous TiO2-SiO2-OCL (Organic chelating Ligand) composite membranes prepared under different firing conditions

Microporous TiO2-SiO2 composite membranes intended for use in the pervaporation dehydration of a water/isopropanol mixture were prepared via the sol–gel method using acetylacetone (ACA) as an organic chelating ligand (OCL). TiO2-SiO2-ACA sols were prepared by using titanium (IV) propoxide (TiTP), an alkoxide of Ti, tetraorthoethylsilicate (TEOS), an alkoxide of Si, and ACA, as a composite of TiO2 and SiO2 with coordinating OCL to Ti. The dried gels were fired at 300 °C under N2 or at 500 °C under air, and were analyzed via FT-IR. Both powders had Ti-O-Si bonds, however, OCL in the powder fired at 500 °C in air has decomposed and removed. The TiO2-SiO2-ACA sols were applied to alumina plates and fired at either 300 °C under N2 or at 500 °C under air to check the water-contact angle, which indicated that the OCL was retained on the plates fired at 300 °C under N2 and were more hydrophobic than when fired at 500 °C under air. TiO2-SiO2-ACA composite membranes were fabricated by coating either the TiO2-SiO2-ACA sol layer fired at 300 °C under N2 or that fired at 500 °C under air onto a TiO2-SiO2 intermediate layer with an α-alumina support. The pore sizes of both membranes were estimated via the NKP method for single-gas permeance at 200 °C. The mean pore sizes of the membranes fired under N2 at 300 °C and under air at 500 °C were 0.47 nm and 0.68 nm, respectively, which suggested the possibility of pore size control via firing conditions. Pervaporation tests of the TiO2-SiO2-ACA composite membranes in a water/isopropanol mixture (IPA: 90 wt%) showed that the membranes fired under air at 500 °C and under N2 at 300 °C had values for permeation flux of 0.90 and 0.13 kg/(m2 h) and separation factors of 667 and 98 at 50 °C, respectively. The higher permeation flux of the membrane fired under air at 500 °C was due to the influence of a larger pore size as well as to a more hydrophilic surface. On the other hand, the separation factor was also higher for the membrane fired under air at 500 °C, because the hydrophilic surface facilitated water permeation. These results indicate the possibility of using firing conditions to control both the pore size and the surface properties of microporous TiO2-SiO2-ACA composite membranes for use in PV separation.

Macro-Meso Damage Analysis of Tunnel Lining Concrete under Thermal-Mechanical Coupling Based on CT Images.

The mechanical properties and failure modes of concrete are controlled by its mesoscopic material composition and structure; therefore, it is necessary to study the deterioration characteristics of tunnel lining concrete under fire from a mesoscopic perspective. However, previous studies mostly analyzed the damage and failure process from a macro-homogeneous perspective, which has certain limitations. In this paper, a thermal-mechanical coupling test device was modified to simulate the state of concrete under tunnel fire conditions. Combined with CT technology, the macroscopic properties and mesoscopic characteristics of concrete were observed. Features were obtained, such as the change in compressive strength under fire, as well as mesoscopic deterioration characteristics. The damage variable D was defined to quantify mesoscopic damage, and the link between mesoscopic deterioration characteristics and macroscopic performance was established, which can be used to predict compressive strength loss through mesoscopic characteristics.

Chemical, mineralogical and physical study of Late Iron Age ceramics from Nditam: Cameroon (West central Africa)

This paper studied Late Iron Age ceramic fragments from Nditam village (Centre Region, Cameroon), the technological features and deduced the type of the raw materials used to produce them by combining different analytical techniques based on X-ray fluorescence, powder X-ray diffraction, thermogravimetry, polarized optical microscopy, spectrophotometry and hydric tests. Macroscopic observations suggest the existence of three types of ceramics according to their colour, black, greyish and red, in the two opposite surfaces, outer (or external) and inner (internal). The chemistry indicates that non-calcareous clayey material was used for ceramic production. The correlation between mineralogy, petrography and the geology of the region suggests a local production of ceramics. Moreover, the chemistry of the samples confirms the existence of the three macroscopic groups and suggests the use of local raw materials for their production. From the mineralogical point of view, quartz, feldspar and mica (biotite and muscovite) were identified in all the samples, while kaolinite and amphibole were detected in some of them. The differences in the mineralogy may indicate some variations in the firing temperature, being lower in the ceramics containing kaolinite compared to the other samples. All the samples have similar water absorption behaviour. According to the colours of the ceramics, a prevalence of oxidising firing conditions was present in the kilns. However, partial reducing and short duration firing conditions were also possible. Comparative study with the mineralogy of ethnographic ceramics from southern Cameroon shows some similarities and suggests a continuity in the use of different local clay pits in this region over time.

About the influence of high temperature or fire testing conditions on the tensile behavior of carbon reinforced poly phenylene sulfide laminates

This study aims to investigate the thermo-mechanical coupling in carbon fibers reinforced Poly Phenylene Sulfide (PPS) laminates subjected to critical temperature conditions. In order to dissociate the physical phenomena (degradation/decomposition on the one hand and deformation/damage mechanisms on the other hand) at play in quasi-isotropic laminates (fiber-dominated mechanical behavior), homogenous and fire testing conditions (heterogenous) were considered with or without mechanical loading. X-Ray tomographic and fractographic analyses were conducted to identify the role played by porosities formation (resulting from thermally induced deformations and damages) on the structural bearing capabilities of C/PPS laminates to be used in high-temperature environments. Under high temperature conditions (homogenous temperature distribution), the retention of tensile properties is not well preserved as the axial stiffness and strength decrease of 50% and 75%, respectively. Under fire conditions (heterogenous temperature distribution), the degradation of tensile properties is more dramatic with an 80% decrease.

Численное моделирование нагрева защитной стенки модели резервуара типа "стакан в стакане" в условиях пожара в основном резервуаре

Introduction. Within the framework of this article, the need to solve a thermal engineering problem aimed at ensuring the fire safety of tanks with a protective wall is substantiated. Computational modeling was also carried out using the developed mathematical model to determine non-stationary temperature fields and stress-strain states that arise in the bodies of a model tank with a protective wall under fire conditions, with a nominal capacity of 700 and 5000 m3. Purpose and objectives. Experimental and theoretical assessment of the non-stationary temperature field of the protective wall of a "glass in a glass" type tank with oil and petroleum products to predict its stability in case of fire. The task is to develop and test a mathematical model in order to carry out numerical simulation of the interaction of a fire flame with the protective wall of a tank to determine its non-stationary temperature fields. Research methods. Numerical modeling was carried out on the basis of a modern computing platform – COMSOL Multiphysics, which allows you to conveniently and accurately simulate complex and complex physical processes, including the interaction of an oil fire flame with the tank body and its protective wall. Results and its discussion. As a result of numerical modeling, the values of the distribution of thermal fields and the stress-strain state on the main tank and the protective wall of the "glass in a glass" type tank were obtained. The calculation results are visualized in the form of isofields, which also allows you to clearly understand the distribution of temperature fields and stresses on each belt of the tank. Conclusions: The results of numerical modeling were obtained to determine the non-stationary temperature fields and stress-strain state that arise in the body of a mathematical model of a tank with a protective wall under fire conditions. The developed and justified numerical modeling method was tested on a reservoir with the most common nominal capacity in operational practice, 5000 m3, with its corresponding geometric parameters. The results of a complex numerical calculation showed that the temperature value of the protective wall body in its upper zone can significantly exceed its critical heating temperature and amount to about 720 °C, at which a stress-strain state occurs. Keywords: reservoir; protective wall; oil; mathematical modeling; mathematical model; fire.

СИЛА ТА МОМЕНТ СИЛИ МАГНУСА. ЇХ ВПЛИВ НА ДАЛЬНІСТЬ СТРІЛЬБИ 155-ММ СНАРЯДІВ

An important component of the main vector of aerodynamic forces and moments of the projectile is the force and moment from the Magnus force, which significantly affect the dynamics of the projectile flight. At the same time, the influence of the Magnus force and moment on the flight of projectiles has been studied relatively little, in addition, the leading scientists of Ballistic Research Laboratories (USA) published quantitative indicators achieved during its calculations, which do not fully meet the requirements for the accuracy of their determination. It is shown that the Magnus force and moment depend on the density of the air, the angular velocity of rotation and the velocity of the projectile, the lateral surface and diameter of the projectile, as well as the angle of its nutation. To evaluate the influence of the Magnus force and moment (their aerodynamic coefficients) on the range of the projectile, a difference method is used, which consists in solving the system of differential equations of spatial motion of a projectile so that changing the value of the aerodynamic coefficient results in a change in the value of the flight range. Numerical modeling of the dependence of the flight range of the 155-mm PF Assegai M2000 projectile and the 155-mm PF ERFB/BB projectile on the change in the magnitude of aerodynamic force and Magnus moment coefficients by 1 % was carried out. It is shown that the aerodynamic force coefficient of Magnus creates the largest errors in the range at the minimum charge, the deviation reaches – 0,005 %, the smallest at the maximum charge – 0,003 %. The largest error in the flight range of the projectile from the aerodynamic coefficient of the Magnus moment is observed at the minimum charge, the deviation reaches 0,6 % D; the effect on other charges leads to much smaller deviations, which are 1-3 orders of magnitude smaller compared to the minimum charge. The obtained results provide an opportunity to assess the required accuracy of determining the aerodynamic coefficients of the Magnus force and the moment of the Magnus force under different conditions of firing by artillery systems.

Механические характеристики стальных конструкций длительного срока эксплуатации при пожаре

The problem of fire resistance of metal building structures with a long service life is considered. The results of a study of the influence of a long service life of steel structures on the physical, chemical and mechanical characteristics (tensile strength, yield strength, relative elongation) at the elevated temperatures in relation to a steel structure with a service life of 92 years are presented. The steel structure was operated under stress conditions — bending under the load of a reinforced concrete flight of stairs. Due to long-term use, traces of the corrosion process are noticeable on its surface over its entire area. The results of the chemical analysis of test samples № 1, 2 are presented. According to GOST 27772—2021, it can be established that the steel under study corresponds to the standard content of the chemical composition of steel of strength class C345, with the exception of a 2-fold increased S content and an insufficient amount of manganese content. With increased sulfur content, steel becomes less strong and the steel resistance to brittle fracture decreases. This is confirmed by earlier work, which showed that increased sulfur content helps to reduce the mechanical characteristics of steel by 2 times. For the first time, the tests were carried out to assess changes in the mechanical characteristics of long-term steel structures under conditions of increased temperature (fire). A comparative analysis of the results of studies of mechanical tests at elevated temperatures for various steel grades was performed. It was established that for the studied samples of steels № 1, 2, long-term natural exposure at temperatures of 500 °C and 600 °C, the yield strength decreases by 23 % and 46 %, and the ultimate strength decreases by 42 % and 50 %, respectively. A tendency for a more intense loss of mechanical characteristics for steel structures of long-term natural aging under fire conditions was revealed.

On the Issue of Ensuring the Durability of Products and Structures Made of High-Strength Concrete to Explosive Destruction

Fire safety procedures are an integral part of the design process of civil and industrial construction facilities. When carrying out design calculations, up-to-date reference data on the resistance of known types of building materials to the effects of open fire and elevated temperatures are used. However, modification of the compositions and properties of such materials may cause changes in their behavior in fire conditions. Thus, new types of high-strength concretes based on Portland cement in practice have shown a tendency to explosive destruction, which significantly affects the reliability of the simulation results of their resistance to prolonged and short-term exposure to elevated temperatures. The presented work provides an overview and assessment of the current state of the issue of ensuring fire safety of structures made of high-strength concrete, additional measures are proposed to improve the existing algorithms for determining their fire resistance.

ДОСЛІДЖЕННЯ ВОГНЕСТІЙКОСТІ ПОКРИТТЯ РЕАКТИВНОГО ТИПУ В УМОВАХ ВУГЛЕВОДНЕВОЇ ПОЖЕЖІ

The purpose of the study is to compare the efficiency of reactive fire protection coatings in modelling scenarios of standard and hydrocarbon fires. Methodology. Fire tests were carried out in a small-scale furnace, as regulated by DSTU EN 16623:2015. The linear coefficient of swelling K was determined in accordance with DSTU-N P B V.1.1-29:2010, and the strength of the char layer was measured using a ST-2 structurometer. The chemical structure of the thermolysis products of the fireproof coatings was studied by IR spectroscopy. Results. The study proposes an experimental protocol for assessing the strength of swollen coatings on steel plates under the influence of a standard and hydrocarbon fire. The evaluation method is based on monitoring the physical integrity and mechanical stability of the char-insulating layer formed from the reactive coating under high temperatures. It has been found that the reactive-type coating under the influence of a standard and hydrocarbon fire forms heat-protective char layers, the degree of swelling, mechanical strength and adhesion of which to the metal plate are proportional and differ on average by up to 10 %. It has been concluded that the studied coating Ammokote MW-120 can be used for fire protection of steel structures operated under potential conditions of hydrocarbon fire. Scientific novelty. The study proposes a simple and reliable method for assessing the possibility of using reactive-type coatings for fire protection of metal structures intended for use and certified for standard fire conditions in hydrocarbon fires. Pactical significance is to expand the scope of application of Ammokote MW-120 coating for fire protection of steel structures under the influence of standard and hydrocarbon fires. Keywords: fire protection of steel structures, hydrocarbon fire, intumescent coating, swelling coefficient.

Обоснование безопасного расстояния между размещенными в одной пожарной зоне кабелями каналов безопасности атомных электростанций с водо-водяными реакторами

Currently, there are no methods of mathematical modeling of the operability of power and signal cables used at the nuclear power plants in real and standard fire conditions, including the use of intumescent flame retardants. The purpose of the article is a theoretical assessment of the safe distance between the cables of the safety channels of nuclear power plants with pressurized water reactors located in the same fire zone. To achieve it, the time of occurrence of a short circuit in the cables of the channels of safety systems from the beginning of a real fire and depending on the distance between adjacent cable lines was estimated. An integral method of mathematical modeling of the development of a fire in a room is used. To determine the temperature distribution inside the cable insulation, the thermal conductivity equation is solved. The analysis of the obtained results is carried out. The calculation results made it possible to formulate the requirements for the swelling temperature of fire retardant compounds for treating the outer surfaces of SB cables: the above temperature should be no more than 150 °C for the flame retardant cables, and 180 °C for the non-flame retardant cables, as well as at distances between open cables of two safety systems smaller than 2, the outer surfaces of the safety cables must be treated with a fire retardant compound with a fire retardant efficiency of at least 120 minutes. The conducted theoretical assessment of the safe distance between the cables of the safety channels of nuclear power plants with pressurized water reactors located in the same fire zone, using the proposed mathematical model, showed that in a real fire, in order to prevent a short circuit in the cables of the safety systems, as well as ignition of the insulation of adjacent cables, it is required to justify safe distances between the adjacent cables of the safety system of nuclear power plants, taking into account the specific dimensions of the premises and the properties of the cable insulation material and the fire-retardant coatings used.

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It has been established that the conditions under which security force units perform their tasks during a full-scale war have undergone significant changes, leading to a decrease in the survivability of security force personnel both during combat operations and while carrying out law enforcement tasks. The main factors influencing the likelihood of a security officer sustaining a combat injury have been identified, and a comprehensive set of survivability indicators for security force personnel under enemy fire conditions has been developed. Based on these indicators, a list of criteria for the survivability of security force personnel has been proposed.

Fire-induced Structural Failure Analysis of an Industrial Warehouse Roof Truss System

Fires are complex and hazardous phenomena governed by the laws of thermodynamics and fluid dynamics. Contrary to common belief, they are not rare occurrences, with approximately 130 buildings in Italy alone experiencing fires daily. The structural behavior under such extreme conditions is difficult to model as material mechanical properties are significantly influenced by temperatures, and thermal deformations alter structural responses.This paper focuses on investigating the fire scenario and the failure of a reinforced concrete industrial warehouse through dynamic fire simulations and nonlinear thermo-mechanical analyses. The warehouse roof is constructed with truss arches featuring three- hinged joints with a steel chain. The arches are regularly spaced at 5.0 m intervals, with a clear span of 19.40 m and a measured height of 8.40 m at the peak and 5.0 m at the supports. The study is composed of two fundamental phases: simulation of fire conditions using Fire Dynamics Simulator (FDS) and investigation of the structural elements collapse through finite element structural analysis.This analysis reveals that, due to thermal stresses, the chain in the roof truss can no longer perform its intended role within the arch, resulting in displacement at the ends and subsequent column collapse. Being a structure designed over 50 years ago, it lacks structural redundancy or robustness.

Научный подход к определению периодичности проведения плановых проверок противопожарного состояния зданий для временного пребывания (проживания) людей

Introduction. Inspections of the fire condition of protection facilities are one of the main activities of the federal state fire supervision of EMERCOM of Russia. Currently, the frequency of scheduled inspections is regulated by the legislation of the Russian Federation in the field of fire safety, depending on the risk category of protection facilities. However, the specified frequency has no scientific justification and is regulated by a strong-willed decision. That is why in recent years the frequency of scheduled inspections has repeatedly changed. Therefore, the development of a scientifically based methodology for determining the optimal frequency of scheduled inspections of the fire state of protected facilities, including buildings for temporary residence (residence) of people, is an urgent problem. Goals and objectives. The purpose of the study was to study the dependence of the number of fires occurring in buildings for temporary stay (residence) of people on the frequency of scheduled inspections of their fire-fighting condition by state fire supervision authorities. The objective of the study is to develop an analytical methodology and substantiate on its basis the optimal frequency of scheduled inspections of the fire condition of buildings for temporary stay (residence) of people. Methods. Based on the analysis of statistical information on fires that occurred in buildings for temporary stay (residence) of people in 2014-2021, analytical dependencies of the average annual number of fires at these protection facilities on the time interval from the moment of their last inspection to the moment of fire occurrence, as well as the number of fires that occurred at the protection facilities of different risk categories on the frequency of scheduled inspections were developed. Results and discussion. As a result of the conducted research, the following has been developed methodology for analyzing statistical information on fires to determine the optimal frequency of scheduled inspections in buildings for temporary residence of people. Unlike the method given in the regulatory legal acts on fire safety, the proposed methodology does not prescribe, but scientifically substantiates the optimal frequency of scheduled inspections. The conducted research allowed us to justify the optimal frequency of scheduled inspections of buildings for temporary stay (residence) of people, which is 0.59 years. Conclusions. The research allowed to prove that the method of regulating the frequency of scheduled inspections given in the normative legal acts on fire safety cannot be universal for all types of supervisory bodies regardless of the type of prevented danger, and the frequency of scheduled inspections significantly depends on the frequency of scheduled inspections of protection objects in previous years. Keywords: state fire supervision bodies; federal state fire supervision; fire protection condition of defense objects; risk category; number of fires; scheduled inspections; frequency of scheduled inspections; optimal frequency of scheduled inspections; legislation in the field of fire safety.